ABSTRACT: The Hart Scott Rodino program, coupled with the modern Merger
Guidelines, has structured merger enforcement for the last twenty
years. This paper tabulates and evaluates information from Federal
Trade Commission merger reviews. While horizontal mergers predominate,
vertical, potential competition and monopsony cases are represented in
the sample. Over the years, the Commission has studied mergers in a
broad range of industries, including branded consumer products,
chemicals, hospitals, drugs, oil, and retailing. Some evolution in the
theories of concern actually used is observed, along with changes in
the efficiency reviews. A statistical model identifies limited evidence
to suggest that enforcement standards change with the political control
of the Federal Trade Commission.